Manufacturers of internal combustion engines typically provide specifications indicating rated (target) power and/or torque outputs of the various manufactured engines over some specified engine speed range or ranges. At least for engines used in medium and heavy duty applications, such specifications are commonly provided as graphs or plots of engine output torque (wherein engine output torque is engine output power divided by engine speed) versus engine speed. An example of one such graph for a known Cummins M11 engine is illustrated in FIG. 1, wherein engine output torque 5 (in Newton-Meters) is plotted over an engine speed range of between 1100 and 1800 RPM.
Within the medium and heavy duty industry, one of the most common complaints from owners of such vehicles is low engine power. Heretofore, a typical technique for investigating such complaints utilized a known fault tree search technique to check all known possible causes of a low engine power condition. However, such a technique does not provide any way to determine or otherwise estimate the actual output power of the suspect engine. In cases where no cause for low engine power is found, the fault tree search technique can, at best, provide an indication that the engine should have the rated power.
What is therefore needed is a system and method for diagnosing engine output power that quickly and efficiently narrows down possible causes for low engine power and further provides a simple and efficient technique for estimating actual engine output power over a desired engine speed range for comparison with rated engine output power specifications. Such a system would provide the equipment owner with improved diagnostic service by reducing misdiagnosis of engine output power related problems and by minimizing unnecessary parts replacement.